Bottle cap



July 18, 1944.

K. CLARK ETAL.

BOTTLE CAP Fi led Nov. 19, 1940 INVENTORS Patented July 18, 1944 BOTTLE CAP Kempton Clark, Little Compton, R. 1., and Herbert G. Vore, Jackson Heights, N. Y., assignors to American Seal-Kap-Corporation of Delaware, Wilmington, DeL, a corporation of Delaware Application November 19, 1940, Serial No.366,218

1 Claim.

This invention relates to bottle caps and more particularly to a partially preformed hood cap for milk bottles or the like.

An object of the invention is to provide a cap of the above type having novel and improved characteristics.

Another object is to provide a cap of the above type having a thermoplastic adhesive coating of such character that it may be readily heat sealed under conditions encountered in commercial operation.

Another object is to provide a partially preformed cap of the above type which may be readily stacked for shipmentand which may be applied to the bottle by standard capping mechanism.

Other objects and advantages will be apparent as the nature of the invention is more fully dis I closed.

Although the novel features which are believed to be characteristic of this invention are pointed out more particularly in the claim appfinded hereto, the invention itself may be better understood by referring to the following description, taken in connection with the accompanying drawing, in which a specific embodiment thereof has been set forth for purposes of illustration.

In the drawing: Fig. 1 is a perspective view of the partially preformed cap as shipped to the dairy;

Fig. 2 is a top plan view thereof; Fig. 3 is a sideelevation, partly broken away, of the'bottle neck and cap, illustrating an intermediate step in the capping and sealing process; and

Fig. 4 is a side elevation, partly broken away, showing the finished cap in place on a milk bottle. a

In the following description and in the claim certain specific terms are used for convenience in referring to various details of the invention. These terms, however, areto be given as broad an interpretation as the state of the art will permit. 1

Referring to the drawing more in detail, the invention is shown as applied to a cap for a standard milk bottle having a neck ill, a pouring lip II and an internal ledge 12 adapted to receive a sealing disc or the like.

In accordance with the present invention the I rigid to be self-supporting and to possess substantial strength.

The paper blank is first moistened with water so as to render the same pliable for subsequent handling. It is then impregnated with a synthetlc thermoplastic resin which is not miscible 'or soluble in wax and which is capable of being heat sealed at comparatively low temperatures. Examples of materials having the above properties are the following: polyvinyl acetate, polyvinyl chloride, the copolymerof vinyl acetate and vinyl chloride, vinylidene resins and their copolymers, modified glyceryl phthalates known as Rezyls and Rezyl-Balsams, and acrylate resins, either with or without non-toxic plasticizers suited to reduce the sealing temperature thereof.

Preferably a resin is used having a sealing tem- Y perature below about 200 F. so as to avoid unduly heating the bottle during the-sealing operation as well as for ease of application in the dairy.

-As a specific embodiment I have found that a polyvinyl resin, such as a suspension of finely divided polyvinyl acetate in an aqueous medium, containing about solids is suitable for the above purpose. The blank, after moistening, may be passed through the suspension and squeezed between rolls to force the same-into the paper and to leave a predetermined coating on the surface thereof. This may take placein two stages if desired. In the first stage the rolls may exert a comparatively high pressure on the blanks so' may be omitted. The amount of water in the.

suspension may be varied to obtain the desired results. A part of the polyvinyl acetate particles 'in the suspension is also forced into the fibers along with the water and serves to impregnate the outer fibers as well as to form a coating over the surface thereof. The coating is thus firmly bonded to the fibers.

After being coated with the thermoplastic resin as above described, the blank is immersed in a wax bath which may comprise paraffin wax heated to a suitable temperature to maintain the same in a liquid condition. The wax serves to drive ofi a part of the water of the suspension and causes the polyvinyl acetate to' become partially set. A portion of the water is allowed to remain in the blank, however, so as to maintain the same pliable for molding. The wax also forms a coating on the surface of the blank which prevents the same from sticking together when they are subsequently stacked.

'After leaving the wax bath, the blanks are cooled to a sufilciently low temperature for the wax to harden, after which they may be stacked and taken to the forming press.

In the forming press the blanks are partially preformed to provide a central, bore-closing portion I5 adapted to seat within the pouring lip II of the bottle II) on the internal ledge I2 thereof, a U-shaped pouring liphousing' I6 joined to the central, bore-closing portion I5 and adapted to cover the pouring lip II of the bottle, and a skirt I'I. folds or pleats I8 which extend outwardly beyond the pouring lip housing l6 and are adapted to be folded downwardly around the outer surface of the bottle neck after the cap has been positioned thereon. The preformed pleats I8 are shown as extending outwardly in about the plane 'of the central bore closing portion I6 but may blanks, serves to maintain the blanks sufllciently pliable for receiving this severe forming operation without tearing the paper. In this condition it is possible to form the pouring lip housing I6 under high pressure so as to form a smooth vertical inner surface 2I. The skirt Il may begin at the top of the outer surface 22 of the pouring lip housing I6 in which case the outer surface is not preformed or a portion of the outer surface 22 above the skirt Il may be preformed. In any event, the skirt forms a continuation of such outer surface when in place on thebottle.

After standingthe remaining water is removed by normal evaporation and allows the cap to set in a semi-rigid condition.

A disc may be inserted within the cap either in the forming press or in a subsequent operation so that the cap, as shipped, includes the disc which is securely held therein to form a single unit. The disc may be heatsealed to the blank and thus secured by the thermoplastic adhesive or may be held in place by the friction of the side wallsof the pouring lip housing. The caps partially preformed, as above described, may be stacked and shipped to the dairy.

At the dairy the caps are applied to the bottle by a suitable capping head which forces the bore closi'ng portion I5 within the bottle neck and folds the pleated skirt downwardly about the outer surface of the pouring lip, as shown in Figs. 3 and 4. Heat and pressure is then brought to bear'upon the folded pleats for rendering the thermoplastic material tacky and causing the pleats to permanently adhere together when the material has again cooled. It is usually desirable to maintain the pressure until the material has cooled to a attained.

In the above described process, the wax coating, in addition to drying and partially setting the polyvinyl acetate, is absorbed within the fibers around the edges of the blank where the susceptibility is the greatest and also at any points on the surface-of the blank where the The skirt I1 is formed with a plurality of point such'that adhesion is resin coating may be incomplete, and thereby increases the water resistance of the blank. The resin coating may be varied so as to provide a substantially wax-free blank or to allow a predetermined amount of wax to be absorbed therein .as desired. The blank may thus be partially impregnated with both wax and resin. Under heat and pressure the wax coating softens and exposes the resin so that the resin coatings of the pleats come into surface contact for sealing.

A small amount of an anti-oxidant may be added to the paraffln' wax bath soas to prevent the bath from oxidizing. The polyvinyl acetate may include a suitable piasticizer so as to render the same heat sealable at temperatures below 200 F. It is usually undesirable to heat the cap when in place on a milk bottle to temperatures greatly above this value. The milk bottle. being cold, readily cools the can after the heating step and facilitates the setting of the thermoplastic resin.

In certain instances a'suitable binding agent, such as aluminum acetate, may be added to the polyvinyl acetate suspension so as to effect a more complete bond with the paper. Such an agent may be present. for example,-In a small proportion such as about 5%. Other materials, such as isomerized rubber (Pliolite), chlorinated rubber, paracoumarone-indene resins, cellulose esters, terpene resins, polybutene or other materials which can be made into a water suspension or emulsion or otherwise incorporated in the polyvinyl acetate suspension may be added thereto for the purpose of increasing the water resistance or improving the sealing qualities.-

Although the above described coating is present on both sides of the blank, nevertheless, the

adhere to the bottle. The cap is accordingly sealed in place solely by the adherence of the pleats, of the skirt to themselves. Hence the cap may be removed without fouling the bottle by merely tearing the same or by breaking the seal between the pleats. In any event, the'cap cannot be re-applied and re-sealed without showing on inspection that the cap has been previously removed.

Obviously, the thermoplastic adhesive coating may be applied to only one side of the blank, if desired, preferably to the side forming the outside of the finished cap. The wax may then be applied to both sides as above described or mail" be applied only to the uncoated side of the blank.

In certain instances it may be desirable to omit the disc 20. However, the disc is usually preferred in order to increase the frictional engagement between the wall of the cap and the inner surface of the pouring lip of the bottle and to assist in holding the cap in place. The use of a disc 20, as shown, permits the cap to be formed from thinner paper than would otherwise be required and thereby decreases the cost of manu-. facture. The use of thin paper also increases the ease of sealing the pleats together.

The above described cap constitutes, in effect, a hood cap which covers the pouring lip of the bottle. The capis formed as a single unit which includes the hood and the disc so that only a single operation is required in capping the bottle. Furthermore, the cap and disc are removed as a unit and in a single operation. The cap is accordingly sanitary, tamper-proof and convenient for the consumer. The wax and resin render the cap moisture proof so that it is not affected by normal conditions of use.

thetic resin having the characteristics required for the above purpose. Other synthetic resins having similar properties and having non-toxic characteristics may also be used.

Although a specific embodiment of the invention has been shown for purposes of illustration, it is to be understood that various changes and modifications may be made therein'as will be readily apparent to a person skilled in the art. The invention is only to'be limited in accordance with the scope of the following cla What is claimed is:

pleated skirt extending downwardly around the outer surface 01' the pouring lip of the bottle, at

least the skirt portion having a coating of a thermoplasticadhesive suited tosecure the folds together comprising essentially polyvinyl acetate which becomes taclgv for sealing at a temperature below about 200 1". and which is set at room temperature, and a wax coating over said adhesive to prevent the caps from sticking together when stacked, said coating being adapted to be displaced to expose the adhesive under sealing conditions of heat and pressure. KEMP'ION CLARK. HERBERT G. VORE.

said cap comprising a bore closing portion and a 

